Selective and non-selective wet-chemical etchants for GaSb-based materials

A series of wet-chemical etchants for materials lattice-matched to GaSb was investigated. The etch rates for GaSb, AlAsSb, InAsSb and InAs with etch solutions based on KNa–tartaric acid (C4H4KNaO6), citric acid (C6H8O7) and hydrochloric acid were determined and the selectivities for the four different etching solutions are shown. The applicability of the selectivity between GaSb and InAs (respectively InAsSb) with C4H4KNaO6:HCl: H2O2:H2O (selectivity higher than 15:1) and C6H8O7:H2O2 (selectivity around 1:100) is proved by a substrate removal experiment. Also a new etchant for AlAsSb is proposed: HCl:H2O2:H2O etches AlAsSb versus GaSb with a selectivity of 5:1 and the GaSb surface underneath is smooth and without any remaining particles of oxidized aluminium.